This invention relates to a fabric for use in the manufacture of tennis balls and to a method of manufacturing the same.
Conventionally, tennis balls are manufactured with the use of a textile having a felted surface. This means that the outer surface of the ball presents a layer of entangled fibres. The felt has a significant influence on the flight characteristics and feel (play characteristics) of a tennis ball. Over the last 50 years a large number of attempts have been made to propose other types, (generally cheaper or having an increased resistance to wear) of non-felted tennis ball coverings but they have been found unsuccessful in equaling the feel and characteristic of the felted fabric and to replace the classic felted covering.
As stated above, tennis balls are manufactured with an outer surface covered with a textile material having a felted surface. The International Tennis Federation Rules of Tennis 2000 states (Rule 3a): xe2x80x9cThe ball shall have a uniform outer surface consisting of a fabric cover . . . xe2x80x9d.
The back surface of the material is smoother and is designed to support the felted outer surface and, when coated with adhesive, provide the necessary characteristics of stretch and adhesion to allow the material to be bonded to the ball.
The conventional method of making a tennis ball felt uses weaving technology to produce a fabric that is first raised or xe2x80x9cnappedxe2x80x9d and then milled to form the felted surface. Alternatively, needlepunch technology can be used whereby a felt is produced from layered webs of fibre that are needled together with or without a supporting scrim. The needlefelt so produced may or may not be subjected to further finishing processes.
Both these methods of felt manufacturing produce a felt with characteristics which are a compromise between the requirements for ball manufacturing and the end product requirements.
Thus, U.S. Pat. No. 4,874,169 describes a game ball having various types of depressions on one of its hemisphere. One particular ball is a tennis ball (see FIG. 5) having one hemisphere covered with a standard tennis ball covering and another covered by a plastic-like smooth material having grooves radiating from its pole.
It has been further proposed in U.S. Pat. No. 1,287,766 to replace the standard fabric covering of the tennis ball by a smooth and soft rubber-like material. Said rubber covering is provided with regular holes in order to mimic the skin friction of a standard tennis ball felt cover.
U.S. Pat. No. 4,616,828 describes a tennis ball having a deep groove extending in the rubber spherical core of the ball in order to control the air turbulence during the ball trajectory. In one embodiment it is proposed to cover the ball with a non-felted fabric made of woven synthetic filaments or fibres. These synthetic filaments are woven so as define a series of rectangular areas.
In U.S. Pat. No. 1,376,778 it is proposed to protect the seam of the textile and to produce a better controlling effect by compressing the outer fabric once provided on a tennis ball at various points along the seam. However, applying pressure to the tennis ball is not recommended as the pressure may alter the internal shape of the core of the ball. Also, compressed area obtained by such compression method are not very wear-resistant and disappear rapidly when used on a tennis ball.
A problem with the modern game of tennis is that as players become more and more powerful, less skill is needed to play the game. The game is fast and rarely are more than two or three shots played in a rally. This makes the games less enjoyable for spectators.
It would be desirable to have a felted tennis ball covering which would allow for greater control over the flight of the tennis ball. More particularly it would be desirable to have a felted tennis covering which, when applied to a tennis ball, alters substantially the flight and/or rebound characteristics when spin is imparted by the player to the ball. This would allow tennis players by imparting spin to various degrees to cause the ball to vary its course to a differing extent as it flies through the air and also to achieve a greater deviation from the expected path of the ball""s rebound from the court.
It was proposed by the Applicant in EP-A-0,974,378 to provide a fabric for use as a tennis ball covering wherein the felted outer surface was composed of entangled fibres and was provided with a three dimensional pattern thereon. Advantageously the three dimensional pattern could comprise a series of depressed and non-depressed areas.
It was also proposed that the fabric comprises at least a support layer and an outer layer, said outer layer having a pattern cut through it and being affixed on the support layer to create said three dimensional pattern. Advantageously, the support layer included a scrim and constituted between 40 and 70% of the weight of the fabric.
Various methods of manufacturing such a fabric were proposed. For example, by interlacing warp and weft threads and generating a three dimensional pattern by varying the interlacing frequency of the warp and weft threads. Alternatively, a three dimensional pattern was created on the fabric by varying the entanglement rate of the fibres of the felted outer surface or by providing at least a support layer and an outer layer, said outer layer having a pattern cut through it and affixing said outer layer on the support layer to create said three dimensional pattern.
Whilst EP-A-0,974,378 discloses the concept of using a composite fabric material for tennis balls, this is only in the context of producing dimpled tennis balls. It has now been realised that a non-dimpled tennis ball can be manufactured by the same technique to provide a fabric material suitable for use as a sports ball covering which enables both the ease of closely fitting a woven fabric around the curvature of the ball, with the benefits of a non-woven outer surface.
U.S. Pat. No. 5,830,092 also describes a composite fabric material for tennis balls, but the face side of that fabric (which forms the outer surface of the covered ball) is formed from non-woven needlefelt and addresses only the difficulties associated with needlepunched felt fabrics.
This invention relates to the production of a composite fabric material for use in covering sports balls (especially tennis balls), and to the balls so produced.
The composite fabric material of the present invention is produced from two or more separate fabric materials which are then laminated together to form a single material.
The invention enables the production of a felted textile material that can be engineered more accurately during manufacturing than those produced by conventional methods. It can thus provide the tennis ball with more specific flight and play characteristics whilst maintaining the optimum characteristics of stretch and flexibility for the manufacture of the ball.
This invention generates a tennis ball covering material having a felted outer surface with an appearance similar to conventional tennis ball material. The material, however, is manufactured in at least two parts. An outer layer which will eventually form the playing surface of the tennis ball; a backing, support layer which will form the surface to be bonded to the core of the tennis ball and, if required, an intermediate layer or number of intermediate layers. These multiple layers are then laminated together to form a single composite material which may itself be subjected to further finishing processes.
Each layer of the composite material so produced may be constructed using different textile manufacturing technologies and be composed of different fibres or blends of fibres and be of different weights, densities and have different physical characteristics.
Thus the outer layer material can be constructed to provide specific wear and performance characteristics appropriate for the tennis ball. It may be produced using woven or non-woven technology. The backing layer may also be produced using woven, non-woven or knitted technology and can be designed to meet the strength and deformation characteristics required for adhesion to the ball. Additionally, if required an intermediate layer or layers can be included to improve the bounce, spin or xe2x80x9cfeelxe2x80x9d of the ball during play.
Further, it has now been discovered that a fabric having small indented areas (herein termed xe2x80x9cdimplesxe2x80x9d) are particularly suitable for the manufacture of tennis ball.
The present invention thus provides a fabric material for use as a sports ball covering, the fabric having a felted outer surface composed of entangled fibres, the outer surface being provided with a three dimensional pattern which comprises a series of dimpled areas, at least some of such dimpled areas each having a surface area ranging from about 3 to 150 mm2, possibly 3 to 115 mm2.
It is preferred that the fabric material be provided with a three-dimensional pattern, preferably a regular pattern, more preferably a pattern of regular dimples, on the outer surface.
Advantageously the pattern can be a pattern of dimples, preferably circular in shape. Alternative shapes of the indentations may be to between 30% and 70% of the full thickness of the fabric and each indentation may have a diameter of, at its widest part, between 2 mm and 12 mm, possibly between 2 mm and 5 mm.
Preferably the adjacent dimpled areas of the fabric material are separated by non-dimpled areas having a minimum width of from 50% to 300% of the diameter of the dimpled areas.
In one embodiment the fabric material may be a composite fabric comprising at least a backing or support layer and an outer layer. Optionally, if a dimpled surface is to be provided, the outer layer will have the pattern cut through it and will be affixed on the support layer to create said three dimensional pattern.
Advantageously, the backing layer constitutes between 40 and 70% of the weight of the composite fabric material. The backing layer may be a woven or a non-woven material. If the backing layer is a non-woven material it preferably includes a scrim.
It is further preferred that the outer layer be a needle felted fabric material.
It is further preferred that the outer layer and backing layer of the composite fabric material of the invention be affixed together using a needle felting technique. Alternatively, the layer of the composite fabric may be affixed together by ultrasonic bonding or thermal bonding (including the use of melt fibres, of scatter coating one fabric with a meltable powder, or of flame bonding).
The invention also relates to a method of manufacturing a composite fabric according to the invention as described above, such method including the steps of:
a) providing an outer layer optionally having a three-dimensional pattern cut therethrough;
b) providing a backing layer; and
c) affixing the two layers together.
It is preferred that step c) be performed by needle punching the outer layer and the backing layer together.
A further object of the invention is the use of the fabric material of the invention to cover a tennis ball.